Glentham is a village and civil parish in the West Lindsey district of Lincolnshire, England. It is situated on the A631, 6 miles (9.7 km) west from Market Rasen, and 2 miles (3.2 km) east from Caenby Corner and the A15. The village includes the hamlet of Caenby. The 2001 Census recorded a population of 341.